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EC and v I C. H. LARSON RELAY Original Filed July 5, 1932 6 3 9 1 8 t P .u

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' justed position by the Reissued Sept. 8-, 1936 UNITED STATES I Re. 20,099

PATENT OFFICE RELAY Carl R. Larson,

of Illinois 1nd., a corporation Original No. 1,967,943, dated July 24, 1934, Serial No. 620,710, July 5, 1932.

Application for reissue June s, 1936, Serial No. 83,818

'11 Claims; (Cl. 200-91) The principal object of this invention is to provide a mercury switch relay that will delay opening a circuit for a selected period after the armature has been raised and will close that circuit immediately after it has been lowered.

Fig. l is a vertical section through a back cone tact .relay, showing the parts in closed circuit position;

Fig. 2 is a similar section, showing the parts just after the magnet has been energized and the displacer raised, but before the circuit has been broken;

Fig. 3 is a similar view, showing the circuit broken;

Fig. 4 is a perspective tion of the displacer; and

Fig. 5 is a sectional view through the upper portion of a modified form of displacer.

But the drawing and the correspondingly specific description are used for the purpose of iilustration and disclosure only, and are not intended to define the scope of the claims.

The glass envelope I is a cylinder sealed oil at the top at H, and having a fiat base I! at the bottom, in which latter lead-in conductors l3 and i4 aresealed. The conductor l3 projects a considerable distance into the envelope, and is surrounded by a glass sleeve l5, fused to the base i2. The conductorsare equipped with suitable terminals [8 and I1. respectively.

Within the envelope is a charge of mercury la, a displacer I9, springs 20 to protect the envelope from the displacer, and a gas fill of helium, hydrogen, or the like. The displacer I9 is made view of the upper porof Swedish iron, on account of its high permeability and low residual magnetism, but of course, may be made of other iron or other magnetic material: It is raised from the position shown in Fig. 1 to that shown in Figs. 2 and 3 by an electromagnet comprising a solenoid 2|, wound on'a spool 22.

The envelope I0 is loosely fitted in soft iron sleeves 23 and 24, clamped by clips 25 to a yoke 28 of laminated iron.' The envelope is held in ari-v iriction of a coil spring 21 of non-magnetic wire, such as phosphor bronze, wound tightly on the envelope and bearing against the adjacent ends of the sleeves 23 and 24.

Externally, the displacer is a plain cylinder with narrow flanges 28 at its top and bottom, recessed at 29 to permit free how of gas or mercury. Internally, the displacer is also a simple cylinder for the major portion of its length, indicated by the bore 30. Above this it is modified to provide a vent for allowing gas to escape rapidly, and

also a small or narrow borefor allowing gas to enter slowly.

. In the specific construction, the drill inserted from the bottom is withdrawn and entered from the top, leaving a partition 3! which is later drilled to a smaller diameter 32. Above the partition is a mass oi burnt asbestos fiber 33, clean hair, steel wool, or the like, and above this is a metal ring 34, having a flaring seat 35, below which is a short cylindrical bore 26. The wall of l the cylinder opposite the asbestos, or the like, has a small or narrow bore 31.

Operation Assuming the parts to be in the position shown in Fig. 1, when the electromagnet is energized, the displacer moves to close the gap between the adjacent ends of the sleeves 23 and 24 and assumes the position substantially as shown in Fig.

2. A globule or meniscus of mercury 38, resting on the seat 15, excludes the ingress of gas except as it can slowly pass through the small or narrow opening 31; hence mercury is drawn up from below, as indicated at 39 (Fig. 2), maintaining the circuit between the electrodes l6 and i1 closed by the mercury. However, in time suflicient gas will enter the bore of the displacer to relieve the partial vacuum, and the mercury will descend to the position shown in Fig. 3, where the circuit is open.

Upon deenergizing the magnet, the displacer will immediately drop to the position shown in Fig. l, by its own weight. At the outset this movement will increase the pressure of the gas within the displacer above the mercury, which will rush easily through the asbestos and pass out between the metal and the mercury globule or meniscus 38, with the result that the displacer raises the mercury level immediately and closes the circuit between the electrodes l8 and i1, as shown in Fig. l. v

The globule or meniscus of mercury 38 will not pass through the asbestos, or other fibrous material, and acts as a check valve, allowing the gas to pass readily out of-the displacer but restraining it from entering the top of the displacer. Just why the mercury will so act is open to some speculation. and no attempt is made to explain the scientific reasons. The fact remains, however, that the mercury will not pass through-the packing 33, and a perfect seal is obtained against ingress of gas. Obviously, the denser the material which constitutes the packing, the less tendency there is for the-mercury globule to be m t d. down- Providing ridges on the seat as shown at II in 3, reduces the tendency the mercury to be drawn downwardly.

'niesmallornarrowboreflmaybeplaced anywhere above the mercury level in the en-' vel pe. but preferably is entered opposite the asbestos or other fiber, because that material acts as a filter in restraining vapor particles. which rise after the circuit is broken and have a tendeasy to collect around any opening and vary the dew through it. The asbestos seems to collect these vapor particles at or near its lower surface and thus maintain the flow through the opening 31 practically uniform.

The check valve arrangement employing a mercury seal is particularly noteworthy because it is virtually impossible to obtain a hermetic seal by the use of a solid ball such as rubber or metal, inasmuch as the gas pressure diil'erentials are comparatively small. The inability to produce a solid ball of metal or other material having exact roundness also renders the use 01 such a check valve impractical for sealing gas.

The time delay may be varied quite widely by changing the proportions. Also by adjusting the envelope with respect to the magnet. In one form that has been found very satisfactory, the displacer has a Y inch external diameter and a 'fiths inch internal diameter. The bore 32 is 5th oi an inch in diameter; the ring it is finds of an inch in vertical dimension; the dam 35 is at an angle of forty-five degrees, and the opening I. is

B/Mths oi an inch in diameter. The cylindrical bore below the ring is nds of an inch long. The small opening 11 is 1/l000th of an inch in diameter, and the time delay is approximately ten seconds, with the envelope and magnet in substantially the position as shown in the drawing.

Although the invention has been shown applied to a back contact relay. it is obvious that it is equally applicable to a front contact relay, in which the electrodes are disconnected when the coil is deenergized. but are bridged with mercury when the displacer is lowered by magnetic n. I claim as my invention:---

1. In a a sealed envelope containing electrodes which, when electrically connected, close an electrica -circuit, a charge oi liquid, a gas fill, and a displacer including a hollow body presenting a wide bottom opening to the liquid and anarrowopeningtothesas, the displaceralso having a gas vent. and a check valve controlling the vent whereby liquid is allowed to enter the dlsplacer rapidly and gas is restricted to slow entry but allowed to escape rapidly from the displacer, said electrodes being arranged so that the opened or closed condition of the switch is determined by the height of the liquid within the point on the displacer with respect to a fixed envelope.

2. In a relay, a sealed envelope containing electrodes which. when electrically connected. close anelectrical cireuit,acharge oiliquid, agasfill, and a displace:- including a hollow body having a wide bottom opening to allow tree entrance and exittoliquidanarrowupperopening topermit slowentranceofseaandaventtoallowi'ree exit of gas, and a check-valve for the vent to-prevent entrance 01' gas through it, the electrodes beingso'arranged'thattheopenedorclosedconditionottheswitchisdeterminedbytheheight oitheliquidwithinthedisplacerwithrespectto 'afimedpointontheenvelope.

thiamercuryswitchrelamasealedenvel opecontainingeiectrodeswnimwhenelechaving a wide bottom opening hollow body.

. point on the envelope.

' comprising a hollow body having a wide bottom opening to allow free flow of mercury into the body, and a vent permitting iree flow of gas out of the body whereby the body may readily descend into the mercury, said body also having a. restricted opening for gas to enter the body and being provided with a mercury valve to check the entrance of gas through the vent, the electrodes being so arranged that the opened or closed condition of the switch is determined by the height'oi the liquid within the displacer with respect to a fixed point on the envelope.

4. In a mercury switch relay, a sealed envelope containing electrodes, a charge of mercury, a gas fill, and a displacer comprising a hollow body to allow free flow of mercury into the body, and a narrow opening above the mercury level to allow restricted flow of gas, the body also having a vent provided with a flaring seat above, and a plug of fibers below the seat allowing tree flow of gas out of the 5. In a mercury switch, a switch envelope, spaced electrodes in the envelope, a gas till, a quantity of mercury in the envelope adapted-to be manipulated, to make or break an electrical circuit through the electrodes, a hollow body presenting a relatively large opening to the mercury and equipped with means for passing gas rapidly through the upper'portion of the body in one direction, but slowly in the other direction, whereby the movement of mercury in the body is retarded in one direction only, saidelectrodes being arranged sothat the opened or closed condition of the switch is determined by the height 01' the mercury within the body with respect to a fixed 6. In a mercury switch, .a switch envelope, spaced electrodes in the envelo a gas iill, a quantity of mercury in the envelope adapted to be manipulated to make or break an electrical circuit through the electrodes, a displacer for changing the mercury level in the envelope, said displacer presenting a relatively large opening to the mercury and being equipped with means for permitting a free escape of gas from the displacer but a slow admittance of gas to the displacer when the large opening is closed by mercury, whereby the movement of mercury within the displacer is retarded when receding only, said closed condition of the switch is determined by with respect to 8 fi d Point on the envelope.

7. For use with a relay 0011, a circuit breaker comprising a switch envelope. spaced-electrodes in the envelope. a gas fill, a mercury fill adapted to make or break an electrical circuit, according to its level, a displacer movable within the envelope in response to the coil for changing the mercury level, and means for effecting unequal time delays for making and the electrical circuit, said means including a valve seat, a porous packingbeneath the seat, and a. globule of mercury resting on the seat.

8.In a mercury switch, a switch envelope, spaced electrodes in the envel pe. a gas fill, a

the opened or whereby movement of mercury to and from the said electrode is timed accordsenting cury level within the gas to pass through the upper portion of thebody more rapidly in one direction than in the other within the body insly.

9. In a mercury switch, a switch envelope, spaced electrodes in the envelope, a gas till, a quantity of mercury in the envelope adapted to be manipulated to make or break an electrical circuit through the electrodes, a hollow body telescoped over one of the electrodes and prea relatively large opening to the mercury and a relative small opening to the gas, and a check valve associated with the body to permit a free passage of gas in one direction only.

10. In a mercury switch, a switch envelope, spaced electrodes in the envelope, 9. gas fill, a quantity of mercury in the envelope adapted to be manipulated to make or break an electrical circuit through the electrodes, a hollow body telescoped over one of the electrodes and presenting a relatively large opening to the mercury and a relatively small opening to the gas, and a check valve associated with the body to permit a free passage of gas in one direction only, said check valve including a valve seat, a globule of mercury on the seat, and means for preventing the globule from being drawn through the seat.

11. In a relay including a coil, a switch envelope, spaced electrodes in the envelope, a gas till, a charge of mercury adapted to make or break a circuit through the electrodes according to its level, a displacer responsive to the coil for changing the mercury level, said displacer presenting a wide opening to the mercury and a relatively small opening to the gas when the former is sub-' merged in the mercury, and a check valve associated with the, displacer for permitting free passage of gas through the displacer in one direction only, said electrodes being arranged so that the opened or closed condition otthe switch is de-* termined-by the height of the mercury level within the displacer with respect to a fixed point on the envelope.

12. In a relay including a coil, a switch envelope, spaced electrodes in the envelope, a gas fill, a charge of mercury adapted to make or break a circuit through the electrodes according. to its level,.a displacer responsive to the coil for changa wide opening to the mercury and a relatively small opening to the gas when the former is submerged in the mercury, and a check valve associated with the displacer for allowing a tree passage of gas from the interior to the exterior of the displacer when the displacer is lowered from its raised positiombut forming a hermetical seal against ingress of gas when .the movement of the displacer is reversed, said electrodes being arranged so that the opened or closed condition or the switch is determined by the height of the merdisplacer with respect to a fixed point on the envelope.

13. In a relay including a coil, a switch envelope, spaced electrodes in the envelope, a gas fill,

a charge mercury adapted to make or break a manipulated to and means for rendering the time delay element ing the mercury level, said displacer presenting circuit through the --electrodes according to its level, a displacer responsive to the coil for changing the mercury level, said displacer presenting a wide opening to. the mercury and a relatively small opening to the gas when the former is submerged in the mercury, and a check valve associated with the displacer for permitting free passage 01 gas through the displacer in one direction only, said check valve including a valve seat, a globule oi mercury resting on the seat, and means for preventing the globule from being drawn through the seat.

14. In a mercury switch, a switch envelope, spaced electrodes in'the envelope, a gas fill, a. quantity of mercury in the envelope adapted to be break an electrical circuit through the electrodes, a time delay element associatedwith one of the electrodes and including a hollow body presenting a relatively large opening to mercury and a relatively small opening to gas,

at times inefiectltve, the electrodes being arranged so that the opened or closed condition of the switch is determined by the height of the liquid within the displacer with respect to a fixed point on the envelope.

15. In a mercury spaced electrodes in the envelope, a gas till, a quantity of mercury in the envelope for bridging the electrodes to close an electrical circuit therethrough, a time delay element telescoped over one of the electrodes and including a hollow body presenting a relatively large opening to mercury and a relatively small opening to gas, and means for rendering the time delay element at times ineffective.

16. In a mercury switch, a switch envelope, spaced electrodes in the envelope, a gas fill, a quantity oi. mercury in the envelope for bridging two electrodes to close an electrical circuit therethrough, a hollow body'telescoped over one or the electrodes and presenting a relatively large opening to the mercury, and means associated with the body for permitting gas to enter and escape therefrom more rapidly in one direction than-in the other whereby the movement of mercury within the body to and from said one electrode is timed accordingly.

17, In a .mercury switch, a switch envelope, spaced electrodes in the envelope, a. gas fill, a quantity of mercury inthe envelope adapted to be manipulated to make or breakan electrical circuit through the electrodes, a time delay element associated with one oi the electrodes and adapted to retard the movement of a portion of the mercury fill in the vicinity of said one electrode, said element including a hollow body telescoped over said one electrode and presenting a, relatively large opening to mercury and a relativelysmall opening to gas, and means for rendering the time delay element effective when the movement of mercury is in a predetermined direction, but ineflective when the movement of mercury is f in the opposite direction. 1 r

- ARL H. LARSON.

switch, a switch envelope, 

